(661e) Scale-up of Agitated Drying: Using Agitator Motor Power Draw to Control Changes in Powder Properties

Scale-up of agitated drying operations to produce Active Pharmaceutical Ingredients (APIs) with the desired powder properties can be challenging. Traditional laboratory drying equipment has not successfully reproduced the degree of agglomeration or attrition observed at scale. The development of new lab-scale tools that can reproduce the magnitude of forces observed during agitation of bulk powders has provided insight into the factors that influence changes in powder properties during API manufacturing. Several recent reports have shown that agitator torque and the total work per unit mass imparted on the drying cake through agitation can be correlated to changes in API particle size. Factors such as API characteristics, batch size, dryer geometry, residual solvent content, and the defined agitation protocol impact the agitator torque, work input, and extent of changes in powder properties during drying. This work builds off these previous reports by using agitator motor power draw, which can be easily measured at both laboratory and pilot plant scale, to compare agitated drying studies conducted at different scales. The application of power measurement to define and implement control strategies for agitated drying of two APIs will be described. In the first case, the power measurement was used to identify an upper limit on agitation and avoid breaking up agglomerates during the drying process. For the second API, the agitator power draw was used to define a lower limit for agitation time to ensure sufficient breakage of needles occurred to provide material with the target bulk density.